[siegel]

Well, I can see the concern if he's not going to be devoting the time and resources that you would be. If you will both be devoted equally, 50-50 (or something similar) might be sense.

But you can solve your concerns without varying the equity division. The company you form only owns the IP you create if your agreement with the company says so. You could agree that, for example, the IP you develop only gets assigned to the company if certain business milestones are met. Or, conversely, you can immediately assign the IP, but have a right to buy it back for a nominal amount if certain milestones are not met by your co-founder.